Vehicle mounted sequential arrow illuminated signs have been in use for several years. Conventionally, they are used by utility and street maintenance crews to route traffic around a work site. Where normal auto and truck traffic are fast moving, on interstate highways for example, the blinking electrically illuminated arrow must be relatively large and must, to be effective, be displayed against a large, properly contrasting background, usually a black, planar surface. State and municipal requirements for these directional traffic regulating displays have recently become more stringent. Larger arrow configurations, containing a minimum of fourteen lamps, (usually of high-intensity sealed beam type) and correspondingly larger background plates or panels are now typical requirements.
Because these large background plates offer substantial aerodynamic resistance, often dangerous, to the transporting vehicle, a rugged, trouble-free, power-operated folding background or display plate provides a highly desirable solution to this problem.
An object of the present invention is to provide a sign, as described above, which, in folded condition, presents a streamlined, triangular prism configuration having minimum drag, with the apex line leading or facing forward in the direction of motion of the vehicle. The movement of the upper and lower plates, into and out of folded position, is accomplished by means of a power-operated lever system which moves the plates smoothly and rapidly and which is enclosed by the plates when they are in folded position. The dual directional arrow configuration formed by the lamps mounted on the hinged plates is such that, with the assembly in folded condition, the central, supporting plate displays horizontally aligned lamps which can be blinked as a non-directional warning or caution signal.